Romania's Prime Minister Mihai Tudose resigned on Monday after his Social Democrat Party (PSD) leaders withdrew backing for him in an overwhelming vote, making him the second premier ousted by the party in less than seven months.

Tensions between Tudose, who was named last June, and the party's powerful president Liviu Dragnea erupted last week when the prime minister asked his interior minister, a close Dragnea ally, to resign, accusing her publicly of lying to him. She refused.

Dragnea retains a tight grip over both the ruling party and government. He is barred from becoming prime minister despite the party's sweeping election win in December 2016 because of a conviction in a vote-rigging case.

Tudose told reporters after the party vote: "I did not want to break the party. They named me, they removed me. I take responsibility for my deeds and I do not regret anything in my actions (as premier)."

He said he would officially submit resignation papers to the country's President Klaus Iohannis tonight or early tomorrow.

"The vote was overwhelming, to dismiss Prime Minister Tudose," one member of the PSD's leadership told Reuters by telephone. "Tudose resigned," another PSD leader said.

Deputy Prime Minister Paul Stanescu will be appointed in his place for an interim period of 45 days, officials said.

The ruling PSD, which has a comfortable parliamentary majority, will have to nominate a replacement for Tudose during the interim period and its nominee needs backing from Iohannis.

The new PSD premier and his team will face a vote of confidence in parliament.

PSD head Dragnea pushed out Tudose's predecessor Sorin Grindeanu as prime minister in a no-confidence vote in June 2017.